Rotary attenuators usually have a braking rotor which is rotatably supported in a housing. There is a viscous fluid in the housing, e.g. silicone oil. When the rotor rotates a respective resistance is produced which makes itself felt as a braking torque. An interaction with a toothed rod or toothed segment which is mounted on the component to be braked becomes possible via a shaft led out of the housing. The shaft has mostly seated thereon a pinion. Such rotary attenuators exist in most varied embodiments. They are employed, above all, in automobiles, electronic devices and the like. They have relatively small dimensions.
Unless particular provisions are made the braking action of such rotary brakes is symmetric. The braking torque obtained in either sense of rotation is approximately the same. However, a one-sided braking effect is desirable in some applications so that freewheeling is intended to act in the inverse direction. Known freewheeling systems require a wrap spring, a bipartite axle as well as an extra metallic bushing with a lubrication to transmit forces. The wrap spring cannot be mounted by automatic machines so that mounting one-way rotary attenuators of this type involves relatively great expenditure.